As such a clamping apparatus, conventionally, there is an apparatus described in the following Patent Document 1 (Japanese Unexamined Patent Publication No. 07-299685). This conventional art is constructed as follows.
A guide hole is opened in a leading end surface of a housing to be attached to a support surface of a stationary table. A clamp rod inserted into the guide hole includes, in the following order in an axial direction: a clamping member provided at a leading end side; a first outer peripheral surface which supports a piston for releasing; a tapered surface with which a pressing surface of an annular collet makes a wedge-engagement from a base end side; and a second outer peripheral surface which supports a piston for locking.
Patent Document 1: JP07-299685